In conventional particle therapy, a charged particle beam accelerated to carry high energy irradiates a malignant tumor such as cancer to treat the tumor.
When a charged particle beam irradiates an object, energy (dose) is applied on the object along a charged particle beam path inside the object. When the dose is applied intensively on a limited area (target) inside the object, the charged particle beam is irradiated from various directions so that the charged particle beam overlaps with the target. This increases the dose concentration.
In the field of particle therapy, generally, a charged particle beam is irradiated from multiple directions to apply more dose to the target in the body, while suppressing exposure of normal tissues. Japanese Patent Laid-Open No. 2002-113118 discloses an apparatus for irradiating a charged particle beam from multiple directions to a target, in which multiple fixed irradiation ports are provided in a treatment room, and a device that varies the property of the charged particle beam is shared among the multiple fixed irradiation ports. Japanese Patent Laid-Open No. 60-20439 discloses an apparatus that irradiates a charged particle beam coming out from a single fixed irradiation port to a target from multiple directions, by rotating the target. Japanese Patent No. 2836446 discloses a rotary irradiation apparatus that rotates an entire charged particle beam transport device.
In the apparatus described in Japanese Patent Laid-Open No. 2002-113118, the number of directions in which the charged particle beam irradiates the target is the same as the number of the fixed irradiation ports. Hence, the directions (irradiation angle) in which the charged particle beam irradiates the target are not continuous. In addition, the same number of charged particle beam transport lines as the number of irradiation directions is required, which causes a problem of production cost and installation space. In the apparatus described in Japanese Patent Laid-Open No. 60-20439, the charged particle beam irradiates the target from various directions by rotating the patient. Hence, there are problems that this is physical and mental burdens on the rotating patient and that the tumor (target) tends to deform due to the rotation. In the apparatus described in Japanese Patent No. 2836446, although the charged particle beam can be irradiated continuously to the target, a large mechanism is required to integrally rotate the transport line and irradiation port of the charged particle beam. This causes a problem of manufacturing cost and installation space of such a mechanism.